Acquired Intangible Assets (Details) (USD $)	3 Months Ended							1 Months Ended	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012		Mar. 31, 2013 Customer Relationships [Member]	Dec. 31, 2012 Customer Relationships [Member]	Feb. 28, 2013 Customer Relationships [Member] SMP Europe [Member]	Mar. 31, 2013 Customer Relationships [Member] SMP Europe [Member]	Mar. 31, 2013 Trademarks and Trade Names [Member]	Dec. 31, 2012 Trademarks and Trade Names [Member]	Mar. 31, 2013 Non-compete Agreements [Member]	Dec. 31, 2012 Non-compete Agreements [Member]	Mar. 31, 2013 Patents and Supply Contracts [Member]	Dec. 31, 2012 Patents and Supply Contracts [Member]	Mar. 31, 2013 Leaseholds [Member]	Dec. 31, 2012 Leaseholds [Member]
Acquired Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Total acquired intangible assets	$ 52,456,000			$ 48,693,000		$ 43,863,000	$ 40,100,000			$ 6,800,000	$ 6,800,000	$ 910,000	$ 910,000	$ 723,000	$ 723,000	$ 160,000	$ 160,000
Less accumulated amortization	(15,547,000)	[1]		(14,210,000)	[1]
Net acquired intangible assets	36,909,000			34,483,000
Intangible assets acquired [Abstract]
Amount of acquired indefinite-lived intangible assets										5,200,000
Amount of acquired intangible assets									3,800,000
Estimated useful life of intangible assets								10 years	10 years
Amortization of acquired intangible assets [Abstract]
Amortization expense	1,300,000		900,000
Estimated amortization expense, remainder of current year	3,600,000
Estimated amortization expense in year 2014	4,500,000
Estimated amortization expense in year 2015	4,300,000
Estimated amortization expense in years 2016 through 2028	$ 19,300,000

[1] Applies to all intangible assets, except for trademarks and trade names totaling $5.2 million, which have indefinite useful lives and, as such, are not being amortized.